JP2014002370A - Autofocus adjustment unit, lens device having the same, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an autofocus adjustment unit which solves a problem that it is difficult to always keep a focused state with respect to a subject moving along an optical axis during photographing moving pictures due to change in a subject speed and change in a subject distance.SOLUTION: An autofocus adjustment unit includes: focus detection means of a phase difference detection method; target position calculation means for calculating a focus lens target position on the basis of a defocus amount and a focus lens position; subject speed calculation means for calculating a subject speed in an optical axis direction on the basis of a current target position, a target position calculated before calculating the current target position, and a target position calculation time taken from a point of time when the target position calculation means has calculated the target position, which is calculated before calculating the current target position, to a point of time when it calculates the current target position; and lens control means for setting a focus lens driving speed on the basis of the current target position, the focus lens position, and the subject speed, and for setting, when no change occurs, the focus lens driving speed on the basis of the current driving speed, a current defocus amount, and a storage defocus amount.

Description

  The present invention relates to an automatic focus adjustment device used for an optical device such as a television lens or a video lens, and more particularly to an automatic focus adjustment used for an optical device having an autofocus function having a focus detection means of a phase difference detection method. The present invention relates to a device, a lens device having the device, and an imaging device.

  2. Description of the Related Art Conventionally, various proposals have been made as AF (autofocus) technology in a photographing apparatus such as a camera or a video camera. For example, an automatic focus adjustment method is well known in which a light beam from a subject that has passed through different exit pupil regions of a photographing lens is imaged on a pair of line sensors, a defocus amount is calculated, and the photographing lens is driven. .

  Patent Document 1 describes the future using a given function based on one or a combination of focal length of a taking lens, subject distance, subject speed, subject acceleration, image plane distance, image plane speed, and image plane acceleration. Discloses a method for predicting the position of the image plane.

JP 2001-021794 A

  In moving image shooting using a camera or a video camera, it is necessary to adjust the focus so that the subject image is always within the depth of field. However, since the prior art disclosed in Patent Document 1 drives a photographing lens based on a given function, photographing conditions that influence individual differences in driving and driving of the lens are considered. Absent. Further, since it is assumed that a still image is taken, it cannot be applied to moving image taking such as a camera or a video camera.

FIG. 9 shows the locus of the focus position of the lens with respect to the subject moving in the optical axis direction. In the figure, the vertical axis represents the subject distance, and the horizontal axis represents time. In FIG. 9, the exposure point at time t1 and t2 is in focus, but the focus state of the lens captures the subject within the depth of field between time t1 and t2 until the exposure point is reached. Is not maintained.
SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic focus adjustment device, a lens device having the same, and an imaging device that can always maintain a focused state regardless of subject speed and subject distance.

  In order to achieve the above object, the automatic focus adjustment apparatus of the present invention includes a defocus amount obtained based on a signal from a focus detection means of a phase difference detection method, and a position of a focus lens obtained by a position detection means. A target position calculating means for calculating the target position of the focus lens based on the target position, a target position storing means for storing the target position calculated by the target position calculating means, the current target position, and the current position The target position calculated before the target position is calculated, and the target position calculation means calculates the target position calculated before the current target position is calculated, and then calculates the current target position. Subject speed calculation means for calculating the subject speed in the optical axis direction based on the target position calculation time required until this time or a time that can be regarded as equivalent to the target position calculation time; First driving speed setting means for setting the driving speed of the focus lens based on the target position, the position of the focus lens, and the subject speed, the current driving speed of the focus lens, A second driving speed setting means for setting a driving speed of the focus lens based on a defocus amount and a defocus amount obtained before the current defocus amount is obtained; If it is determined that the subject speed has changed, the focus lens is driven based on the driving speed by the first driving speed setting means, and it is determined that the subject speed has not changed. And a lens control means for driving the focus lens based on the driving speed by the second driving speed setting means. .

  According to the present invention, it is possible to provide an automatic focus adjustment device capable of maintaining a focused state for a subject moving in the optical axis direction regardless of subject speed and subject distance. In addition, the focus lens drive speed is relatively increased or decreased based on the increase / decrease of the defocus amount, so that the in-focus state is maintained for the subject moving in the optical axis direction regardless of the environmental and temporal changes in lens characteristics. Thus, it is possible to provide an automatic focus adjustment device that can be used, a lens device including the same, and an imaging device.

Configuration diagram of the first embodiment Main flowchart of the first embodiment Focus lens drive speed adjustment process flowchart of the first embodiment Focus lens drive speed adjustment process flowchart of the first embodiment Lens focal length locus applied with the first embodiment The figure explaining judgment of the focus lens drive speed in the 1st example Configuration diagram of the second embodiment Flow chart of the second embodiment Trajectory of focal length of conventional lens

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a configuration of a lens apparatus 100 which is a first embodiment of an automatic focus adjustment apparatus of the present invention. The lens apparatus 100 has an optical system including a focus lens 101. The lens device 100 constitutes an imaging device 300 together with the camera device 200. The lens apparatus 100 moves the focus lens 101 in the optical axis direction to change the position of the image formation plane of the lens apparatus 100.

  A focus motor 102 is connected to the focus lens 101. The focus motor 102 is driven by the focus driver 103 and moves the focus lens 101 in the optical axis direction. The focus motor 102 and the focus driver 103 constitute a focus lens driving unit. The position of the focus lens 101 is detected by a focus lens position detection unit 104 serving as a position detection unit.

  The zoom lens 105 moves in the optical axis direction and changes the focal length of the lens apparatus 100. A zoom motor 106 is connected to the zoom lens 105. The zoom motor 106 is driven by a zoom driver 107 and moves the zoom lens 105 in the optical axis direction. The zoom motor 106 and the zoom driver 107 constitute zoom drive means. The position of the zoom lens 105 is detected by the zoom lens position detector 108.

  An iris motor 110 is connected to the movable diaphragm (aperture diaphragm) 109. The iris motor 110 is driven by the iris driver 111 and drives the movable diaphragm 109. The iris motor 110 and the iris driver 111 constitute an iris driving means. The position (opening degree) of the movable diaphragm 109 is detected by the iris position detection unit 112.

  The spectroscopic prism 113 splits the light transmitted through the focus lens 101 and the zoom lens 105 into two light beams. One light beam transmitted through the spectroscopic prism 113 enters the image sensor 124 through the relay lens 123. The other light beam reflected by the spectroscopic prism 113 is incident on a phase difference detection type focus detection unit 114 as focus detection means. The focus detection unit 114 includes a phase difference detection lens and a phase difference detection sensor, and photoelectrically converts a pair of images (two images) formed by two light beams separated by the phase difference detection lens using the phase difference sensor.

  A lens control unit 115 as a lens control unit controls driving of a focus lens driving unit, a zoom lens driving unit, and an iris driving unit. A defocus amount calculation unit 117 serving as a defocus amount calculation means calculates a phase difference between a pair of image signals that are part of a photographic light beam photoelectrically converted by the focus detection unit 114 to calculate a defocus amount for a predetermined subject. Is calculated. The depth of field calculation unit 116 as a depth of field calculation means focuses on the subject to be focused based on the position information of the focus lens 101, the zoom lens 105, and the movable aperture 109, and the defocus amount. Is calculated (or may be read from a table). A focus lens target position calculation unit 118 serving as target position calculation means calculates a focus lens target position from the defocus amount calculated by the defocus amount calculation unit 117 and the position information of the focus lens position detection unit 104. In the subject speed calculation unit 119 as the subject speed calculation means, the time required by the focus lens target position calculation unit 118 (target position calculation time) or the focus detection unit 114 performs focus detection (acquisition of the pair of image signals). Based on the required time and information from the focus lens target position calculation unit 118, the moving speed of the subject in the optical axis direction is calculated. The focus lens drive amount calculation unit 120 serving as a drive amount calculation unit calculates the drive amount of the focus lens 101 based on information from the focus lens target position calculation unit 118 and the focus lens position detection unit 104. The focus lens drive speed setting unit 121 as the first drive speed setting unit sets the focus lens drive speed based on information from the focus lens drive amount calculation unit 120 and the subject speed calculation unit 119. Although the focus lens driving speed setting unit 121 is the first driving speed setting unit, a unit having both the function of the focus lens driving amount calculation unit 120 and the function of the focus lens driving speed setting unit 121 is used as the first driving speed setting unit. Also good.

  In the focus lens drive speed adjustment unit 122 as the second drive speed setting means, information from the depth of field calculation unit 116, the subject speed calculation unit 119, the focus lens drive speed setting unit 121, and the defocus amount calculation unit 117 is used. Based on this, it is determined whether the focus lens drive speed is appropriate for the subject speed. If it is determined as inappropriate, the focus lens drive speed is changed.

  The above-described configuration will be described in detail using the flowchart of FIG. 2, the focus lens driving speed adjustment process flowchart of FIG. 3, and the lens focal length locus of FIG. 5.

  In S201 of FIG. 2, the defocus amount calculation unit 117 calculates a defocus amount by calculating a phase difference between a pair of image signals that are part of the photographing light beam photoelectrically converted by the focus detection unit 114. In step S202, the focus lens position detected by the focus lens position detection unit 104 is read. In S203, the zoom lens position detected by the zoom lens position detection unit 108 is read. In S204, the iris position detected by the iris position detector 112 is read. In S205, the depth-of-field calculating unit 116 is in focus on the subject to be focused by Expression (1) and Expression (2) based on the focus lens position, the zoom lens position, and the iris position. Compute the forward and backward depth of field.

Forward depth of field = (σ × Fno × L × L) / (f × f−σ × Fno × L) (1)
Back depth of field = (σ × Fno × L × L) / (f × f + σ × Fno × L) (2)
Here, σ is the diameter of the allowable circle of confusion, f is the focal length, L is the subject distance, and Fno is the F number. Here, the description has been made assuming that the depth of field is calculated by the above formula, but the present invention is not limited to this, and it may be read from a table or the like. Further, the diameter σ of the permissible circle of confusion is a known value determined by the type (size, pixel pitch) of the image sensor, the application (imaging form), and the like. For example, the diameter σ of the permissible circle of confusion is 0.04mm for the image sensor size (image size) P (1 1/4 "), 0.03mm for PV (1"), and 0.021 for J (2/3 "). For mm and PH (1/2 "), the standard is 0.016 mm. In addition, it is one guideline that the diameter σ of the permissible circle of confusion is 0.5 to 2 times the pixel pitch. Zoom lens position when the defocus amount is calculated by controlling the focus lens to be within the range of the forward depth of field and the backward depth of field based on the subject distance calculated here In the iris state, the in-focus state can be maintained.

  In S206, the focus lens target position calculation unit 118 calculates a focus lens target position corresponding to the current subject distance from the defocus amount calculated in S201 and the focus lens position read in S202. In S207, the focus lens drive amount calculation unit 120 calculates the drive amount of the focus lens 101 based on the current focus lens target position calculated in S206 and the focus lens position read in S202. In S208, the subject speed calculation unit 119 is time required for calculation by the focus lens target position calculation unit 118 (target position calculation time) or time required for focus detection (acquisition of the pair of image signals) by the focus detection unit 114. Current focus lens target position and at least one previous focus lens target position stored in a target position storage means (not shown) (the focus lens target position calculated before the current focus lens target position is calculated) ), The subject speed in the optical axis direction is calculated using equation (3). Hereinafter, for simplification of description, the subject speed is described as the subject speed and represents the subject speed in the optical axis direction.

V = (fctl−fctl0) / T (3)
Here, V is the change in the focus lens target position per unit time (the subject speed can be obtained from the change in the focus lens target position per unit time. Also, in the following processing, the focus lens target position Instead of the change, the subject speed may be used, and hence V is referred to as “subject speed” in the following. fctl indicates the current focus lens target position, and fctl0 indicates at least one previous focus lens target position. In T, the focus lens target position calculation unit 118 calculates the at least one previous focus lens target position fctl0 (the focus lens target position fctl0 calculated before the current focus lens target position is calculated). Represents the time (target position calculation time) that has elapsed since the current focus lens target position fctl was calculated. As T, in addition to the target position calculation time, a time that can be regarded as equivalent to the target position calculation time may be used. As the time that can be regarded as equivalent to the target position calculation time, for example, the focus detection unit 114 acquires the pair of image signals necessary for the calculation of the at least one previous focus lens target position fctl0, and then the focus You may use the time (focus detection time) which passed until acquiring a pair of image signal required for calculation of lens target position fctl. Here, V is positive in the direction of moving to the far side. In S209, the subject speed Vnow calculated in S208 is subtracted from the subject speed V0 calculated in at least the previous processing loop and stored in a storage unit (not shown) in the lens control unit 115 to obtain the subject speed. A change amount ΔV is calculated.
ΔV = Vnow−V0 (4)

In S210, it is determined whether or not the subject speed has changed within a predetermined time by the following equation (5).
| ΔV | <α1 (5)
Here, α1 is a predetermined positive threshold value (first threshold value). When the absolute value of the subject speed change amount ΔV is equal to or greater than α1 (greater than or equal to the first threshold) in Expression (5), it is determined that the subject speed has changed, and the process proceeds to S211. When the subject has not moved in the optical axis direction, that is, when the subject speed V0 stored in the storage unit (not shown) in the lens control unit 115 is 0, the process proceeds to S211. When the absolute value of the subject speed change amount ΔV is smaller than α1, it is determined that the subject speed has not changed, and the process proceeds to S212. In S212, the focus lens drive speed adjustment unit 122 determines whether the current focus lens drive speed is appropriate for the subject speed calculated in S208. In S211, the focus lens drive speed setting unit 121 reads the focus lens drive speed from the table based on the focus lens drive amount calculated in S207 and the subject speed calculated in S208 (or may be obtained by calculation). ) Set and move to S213.

FIG. 3 shows details of processing in the focus lens drive speed adjustment unit 122 in S212. In S301 in FIG. 3, at least one previous defocus amount d0 stored in a defocus amount storage unit (not shown) is subtracted from the current defocus amount dnow calculated in S201, and within a predetermined time. The defocus amount change amount Δd is calculated.
Δd = dnow−d0 (6)

In S302, based on the focus lens position read in S202, the depth of field calculated in S205, and the defocus amount calculated in S201, it is determined whether the focus lens is currently positioned within the depth of field. judge. If the focus lens is located within the depth of field, the process proceeds to S303. If the focus lens is not located within the depth of field, the process proceeds to S304. In S303 and S304, it is determined whether or not the current focus lens drive speed is appropriate for the current subject speed. In S303, it is determined whether the current focus lens drive speed is appropriate using Expression (7).
| Δd | <α2 (7)
Here, α2 represents a positive threshold value (second threshold value). When the absolute value of the change amount Δd of the defocus amount is α2 or more (second threshold or more), it is determined that the focus lens drive speed is inappropriate, and the process proceeds to S305. When the absolute value of the change amount Δd of the defocus amount is smaller than α2, it is determined that the focus lens drive speed is appropriate, the focus lens drive speed adjustment process is terminated, and the process proceeds to S213 in FIG.

In S304, it is determined whether or not the current focus lens driving speed is appropriate depending on whether or not both the expressions (8) and (9) are satisfied.
| Δd |> α3 (8)
| Dnow | <| d0 | (9)
Here, α3 represents a positive threshold value (third threshold value). If the absolute value of the defocus amount change Δd is less than or equal to α3 (below the third threshold) or the absolute value of dnow is greater than or equal to the absolute value of d0, it is determined that the focus lens drive speed is inappropriate and the process proceeds to S305. To do. When the absolute value of the change amount Δd of the defocus amount is larger than α3 and the absolute value of dnow is smaller than the absolute value of d0, it is determined that the focus lens drive speed is appropriate, and the focus lens drive speed adjustment process is terminated. The process proceeds to S213.

In S305, it is determined whether or not the subject moving direction (the sign of the subject speed V) matches the sign of the current defocus amount dnow obtained in S201. Here, as to the sign of the subject moving direction, as described above, the front depth of field side is negative, and the rear depth of field side is positive. The sign of the current defocus amount dnow is positive when the actual subject distance is on the far side with respect to the focused object distance of the focus lens, and is negative when the actual subject distance is on the near side. Take the value.
If the sign of the subject movement direction and the current defocus amount are the same, the process proceeds to S306, and if the sign is different, the process proceeds to S307.

In S306 and S307, the absolute value of the defocus amount dnow calculated in the current routine is calculated at least in the previous processing loop and stored in a storage unit (not shown) (current defocus amount d0). It is determined whether or not the absolute value of the defocus amount d0) obtained before the amount is obtained has decreased.
| dnow | <| d0 | (10)
In the case of d2 in FIG. 5, it is determined that the absolute value of the defocus amount is increased, and in the case of d3, the absolute value of the defocus amount is decreased.

In S306, using Expression (10), if | dnow | is smaller than | d0 |, the process proceeds to S308, and if | dnow | is equal to or greater than | d0 |, the process proceeds to S309. In S307, if | dnow | is smaller than | d0 | using Expression (10), the process proceeds to S311. If | dnow | is equal to or greater than | d0 |, the process proceeds to S310. In S308 and S310, using the equation (11), the current focus lens is decelerated while maintaining the moving direction (the drive speed between times t1 and t2 in FIG. 5 is decelerated to a speed after t2), and The focus lens drive speed adjustment process is terminated, and the process proceeds to S213 in FIG. In S309 and S311, using the equation (11), the current focus lens is accelerated while maintaining the moving direction (the driving speed before time t1 in FIG. 5 is accelerated to a speed between t1 and t2), and The focus lens drive speed adjustment process is terminated, and the process proceeds to S213 in FIG.
Xnew = Xnow + β × γ (11)
Here, Xnew is the focus lens drive speed calculated in S308, S309, S310 and S311, Xnow is the current focus lens drive speed, and β is based on the current defocus amount and at least the previous defocus amount. The determined value, γ, represents an arbitrary constant.

  Here, the processing of S305 to S311 in FIG. 3 will be described in detail with reference to FIGS. 6 (a) and 6 (b). The process proceeds from S303 to S305 when the subject distance changes in one direction under a constant speed condition (S210), and the position of the focus lens is within the depth of field with reference to the subject distance. . Further, this is the case where the absolute value of the defocus amount difference is equal to or greater than a predetermined threshold (S303), which means that the defocus amount change speed is equal to or greater than a predetermined magnitude. If the process proceeds from S304 to S305, the focus lens position is not within the depth of field with reference to the subject distance (S302), and the focus lens is subject to the subject at a predetermined speed or more. This is a case where it has not moved toward the position (S304). This state is classified for the defocus amount and the sign of the subject movement direction. When the subject movement direction is positive (the subject distance has changed to the far side) in FIG. 6A, the subject is shown in FIG. The case where the moving direction is negative (the subject distance has changed to the short distance side) is shown.

  In FIG. 6A, at time t1, the defocus amount obtained in S201 is negative (the focus lens position is on the far side from the subject distance) and positive (from the subject distance). The focus lens position is on the short distance side (B0). The case where the focus lens in the state of A0 and B0 changes in parallel with the change in the subject distance is indicated by a dotted line in this figure. In this case, the defocus amount at time t1 and the defocus amount at time t2 change. There is no. On the other hand, considering the sign that the long distance side is positive, if the focus lens position changes from A0 to A1, or changes from B0 to B2, the absolute value of the defocus amount increases. Yes. At this time, in order to be closer to the in-focus position, the vehicle is decelerated in the case of A1 and accelerated in the case of B2. In addition, when the focus lens position changes from A0 to A2, or when it changes from B0 to B1, the absolute value of the defocus amount decreases. At this time, acceleration is performed in the case of A2 and deceleration is performed in the case of B1, so as not to approach the focusing position too quickly or pass through the focusing position.

  In FIG. 6B, at time t1, the defocus amount obtained in S201 is negative (the position of the focus lens is on the far side from the subject distance) and positive (from the subject distance). The focus lens position is on the short distance side (D0). The case where the focus lens at C0 and D0 changes in parallel with the change in the subject distance is indicated by a dotted line in this figure. In this case, there is no change in the defocus amount at time t1 and the defocus amount at time t2. . On the other hand, considering the sign that the long distance side is positive, if the focus lens position changes from C0 to C1, or changes from D0 to D2, the absolute value of the defocus amount increases. Yes. At this time, in order to get closer to the in-focus position, acceleration is performed in the case of C1, and deceleration is performed in the case of D2. In addition, when the position of the focus lens changes from C0 to C2, or when the focus lens changes from D0 to D1, the absolute value of the defocus amount decreases. At this time, the speed is reduced in the case of C2, and the speed is accelerated in the case of D1, so as not to approach the in-focus position too quickly.

  Note that the processing from S305 to S311 of the focus lens driving speed adjustment processing shown in FIG. 3 can be collectively described as S320 to S322 as shown in FIG. If the determination in S303 and S304 is “No”, the process proceeds to S320. In S320, whether or not the defocus amount including the sign is increased or decreased is determined instead of the determination based on the absolute value of the defocus amount in S306 and S307 in the processing of FIG. If the current defocus amount has decreased from the previous time, the process proceeds to S321, and if the current defocus amount is equal to or greater than the previous defocus, the process proceeds to S322. In S321 and S322, the current driving speed of the focus lens is accelerated / decelerated with the driving direction of the focus lens that moves the in-focus position toward infinity as positive and without changing the driving direction. Specifically, in S321, the current drive speed is decelerated (in the case of driving that moves the in-focus position to the infinity side, the drive speed is decreased by Δ1 (Δ1> 0), and the in-focus position is moved to the closest side. In the case of driving, the driving speed is increased by Δ1). In S322, the current driving speed is accelerated (the driving speed is increased by Δ2 (Δ2> 0 in the case of driving to move the in-focus position to infinity), and the driving speed is moved in the case of driving to move the in-focus position to the closest side). Decrease the speed by Δ2).

  In S213, the subject speed calculated in S208 is stored in a storage unit (not shown) in the lens control unit 115, and in S214, the defocus amount calculated in S205 is stored in the storage unit. In S215, the focus lens target position calculated in S206 is stored in the storage unit, and the process proceeds to S216. In S216, the focus is driven at the focus lens driving speed set in the above-described operation, and the process returns to S201 to repeat a series of operations.

  FIG. 7 is a block diagram of a second embodiment of the automatic focus adjustment apparatus of the present invention. The description of the same configuration as that of the first embodiment shown in FIG. 1 will be omitted, and the parts different from the first embodiment will be described below.

  In addition to the first embodiment, the automatic focus adjustment apparatus of the second embodiment includes a threshold value changing unit 505, a switch 501 (first changing means), 502 (second changing means), and 503 (third change). Means) and 504 (fourth changing means).

  The threshold value changing unit 505 is an arbitrary input from the switches 501, 502, 503, and 504 using the threshold values α 1, α 2, α 3 and the constant γ in the equations (5), (7), (8) and (11) as changing means Change to the value of. Here, for ease of explanation, an input of an arbitrary value is used as a switch. However, if an arbitrary value can be set, it is not necessary to be a switch.

  The operation in this configuration will be described with reference to the flowchart of FIG. 8, S201 to S215 are the same as those in the flowchart of FIG. In S601, the threshold value changing unit 505 determines whether there is a request for changing the threshold value in the switches 501, 502, 503, and 504. If there is a change request, the process proceeds to S602. If there is no change, the process proceeds to S201. In step S602, the threshold value changing unit 505 reads the value input by the switch 501 and changes the subject speed change criterion threshold value (α1 in equation (5)) to the read arbitrary value. In S603, the threshold value changing unit 505 reads the input value from the switch 502, and when the current focus lens is within the depth of field, the current defocus amount has changed relative to at least the previous defocus amount. The threshold value (α2) for determining whether or not is changed to the input value. In S604, the threshold value changing unit 505 reads the input value from the switch 503, and when the current focus lens is outside the depth of field, the current defocus amount has changed with respect to at least the previous defocus amount. The reference threshold value (α3) for judging whether or not is changed to the input value. In S605, the threshold value changing unit 505 reads the input value from the switch 504, changes the sensitivity (γ) for adjusting the current focus lens driving speed to the input value, and proceeds to S201. In S216, the focus is driven at the set focus lens driving speed, and the process returns to S601 to repeat a series of operations.

  In the above embodiment, the control is exemplified such that the focus lens is positioned within the front and rear depths of field on the assumption that the focus lens is focused on the subject distance. It is not limited to. It should be noted that the above-described effects of the present invention can be obtained even by controlling the subject to be captured within the front and rear depths of field based on the current focus lens position.

  In the illustrated embodiment, a part of the photographing light beam is divided and guided to the focus detection unit 114 to calculate the defocus amount. However, the present invention is not limited to this configuration. For example, the effect of the present invention can be enjoyed even if a focus detection optical system is provided separately from the photographing optical system and the defocus amount is calculated by a light beam that passes through the optical system.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. An imaging apparatus including a lens apparatus including the automatic focus adjustment apparatus of the present invention or a camera apparatus having an imaging element that receives subject light from the lens apparatus and the lens apparatus enjoys the effects of the present invention described above. can do.

  The present invention is applicable to optical devices such as TV lenses and video lenses, and particularly to optical devices having an autofocus function.

100: Lens device 101: Focus lens 114: Focus detection unit (focus detection means)
115: Lens control unit 118: Focus lens target position calculation unit (target position calculation means)
119: Subject speed calculation unit (subject speed calculation means)
121: Focus lens driving speed setting unit (first driving speed setting means)
122: Focus lens driving speed adjusting unit (second driving speed setting means)

Claims (12)

Target position calculation for calculating the target position of the focus lens based on the defocus amount obtained based on the signal from the focus detection means of the phase difference detection method and the position of the focus lens obtained by the position detection means Means,
Target position storage means for storing the target position calculated by the target position calculation means;
The current target position, the target position calculated before the current target position is calculated, and the target position calculation means calculates the target position calculated before the current target position is calculated. Subject speed calculation for calculating the subject speed in the optical axis direction based on the target position calculation time required to calculate the current target position or the time that can be regarded as equivalent to the target position calculation time Means,
First driving speed setting means for setting the driving speed of the focus lens based on the current target position, the position of the focus lens, and the subject speed;
A second that sets the focus lens drive speed based on the current drive speed of the focus lens, the current defocus amount, and the defocus amount obtained before the current defocus amount is obtained; Drive speed setting means,
It is determined whether or not the subject speed has changed. If it is determined that the subject speed has changed, the focus lens is driven based on the driving speed by the first driving speed setting means, and the subject speed changes. A lens control unit that drives the focus lens based on the driving speed of the second driving speed setting unit when it is determined that the second driving speed setting unit does not;
An automatic focus adjustment device characterized by comprising:   The lens control means determines that the subject speed has not changed when the absolute value of the change amount of the subject speed is smaller than the first threshold value, and the absolute value of the change amount of the subject speed is the first threshold value. 2. The automatic focus adjustment apparatus according to claim 1, wherein if it is above, it is determined that the subject speed has changed. A depth-of-field calculating means for calculating the depth of field based on the state of the optical system;
The second drive speed setting means is configured such that the current subject is within the depth of field calculated by the depth of field calculation means, and the absolute value of the defocus amount change amount within a predetermined time is the second value. When the driving speed of the focus lens is changed,
The automatic focus adjustment apparatus according to claim 1 or 2, characterized in that: A depth-of-field calculating means for calculating the depth of field based on the state of the optical system;
The second drive speed setting means is configured such that the current subject is not within the depth of field calculated by the depth of field calculation means and the absolute value of the change amount of the defocus amount within a predetermined time is obtained. If the current object is not within the depth of field and the absolute value of the current defocus amount is equal to the defocus amount obtained before the current defocus amount is obtained, or less than the third threshold When the absolute value is exceeded, the driving speed of the focus lens is changed.
The automatic focus adjustment apparatus according to claim 1 or 2, characterized in that:   When the defocus amount is decreased, the change of the focus lens drive speed by the second drive speed setting means is reduced when the focus lens is driven to the infinity side, and is moved closer to the closest side. Accelerates when driving, and when the defocus amount does not increase or change, it accelerates when the focus lens is driving to infinity, and when driving to the closest side The automatic focus adjusting apparatus according to claim 3, wherein the motor decelerates.   The automatic focus adjustment apparatus according to claim 2, further comprising a changing unit that changes the first threshold value to an arbitrary value.   The automatic focus adjustment apparatus according to claim 3, further comprising a changing unit that changes the second threshold value to an arbitrary value.   5. The automatic focus adjustment apparatus according to claim 4, further comprising changing means for changing the third threshold value to an arbitrary value. The depth-of-field calculating means calculates the depth of field based on the position of the focus lens, the position of the zoom lens, and the position of the aperture stop obtained by the position detecting means;
The automatic focus adjustment apparatus according to claim 3 or 4, wherein The automatic focus adjustment apparatus according to any one of claims 1, 2, and 6,
The focus lens;
The position detecting means for detecting the position of the focus lens;
A lens apparatus comprising: An automatic focus adjustment device according to claim 9,
The optical system having a focus lens, a zoom lens, and an aperture stop;
The position detecting means for detecting the position of the focus lens, the position of the zoom lens, and the position of the aperture stop;
A lens apparatus comprising: The lens device according to claim 10 or 11,
And a camera device having an image sensor for receiving subject light from the lens device.

Images